This invention relates to a device for preventing movement of substrates on the platen of electrostatic copying machines and more particularly to a device for preventing movement of original documents being copied on electrostatic copying machines employing a reciprocating platen.
Conventionally, the original document on the platen which reciprocates in an electrostatic copying machine has been moved by the impact caused by the reciprocative movement of the platen, and when a plurality of copies are being made, the reproduced image seldom appears at the same position on each copy.
As shown in FIG. 1, a platen 2 on the copying machine body 1 moves reciprocatively in the direction as shown in arrow A in synchronization with the other portions of the copying machine body. This reciprocative movement is subjected to impact more or less when the movement changes in direction from leftward to rightward or from rightward to leftward. The aforementioned platen 2, as shown in FIG. 2, comprises a platen frame 4 which retains a platen glass 3 and a platen cover 5. An original substrate or document 6 is placed between the platen glass 3 and the platen cover 5 in normal operation with the edge of the original document being placed in alignment with the edge of the platen frame 4 as shown in FIG. 3. The substrate 6 moves in the direction as shown by arrow B due to the impact caused by the reciprocative movement of the platen 2, as mentioned above. This movement of the original document 6 is found to be more pronounced when producing a plurality of copies of the same document.
A solution to the above-mentioned problem is required before one can rely on perfectly aligned copies exiting from copying machines employing reciprocating platens.
Accordingly, it is an object of this invention to provide a device for preventing movement of a substrate that is being copied from a reciprocating platen, that is simple in structure.
Yet another object of this invention is to provide a space creation means in association with a platen cover that allows the removal of a document from a platen with the vacuum associated therewith being substantially reduced.
Yet another object of this invention is to provide a pressure concentration means for applying weight to a substrate on the platen of the copying machine in order to prevent movement of said substrate.